04-12-2017, 03:53 AM
(04-12-2017, 03:14 AM)Raypat Wrote: I received my controller board for the igaging digimax scales a few days ago. After carefully mounting two mini usb breakout boards and the controller board in a plastic box I soldered them up checking and re checking the connections. When it came time to power it up I was confident everything was connected correctly. I am only using two outputs because I do not have z axis dro at the moment.The only doubt I had was the polarity of the power supply as I had to source a different connector to suit the board. I connected positive to the centre of the plug and tested it with a meter. The voltage polarity seemed correct with a positive reading so I powered up the board. Everything worked as expected with the three leds flashing. Just to be sure I put a meter across the output voltage to the scales. With the red lead of my meter to 3v and the black lead to ground I got a negative voltage at this point. Thinking I had the polarity reversed I quickly unplugged the power supply and reversed the leads to the plug. You can guess by now what happened next. On power up I got instant smoke and the board is now dead. My question is can the board be repaired by me (a machinist rather than an electrician) or have I made a hundred buck mistake? Also is it to be expected to get a negative voltage at the output to the scales? Thanks in advance to anyone who can help.
It's not normal to see negative voltage across the scale power supply. It's unlikely that that was the case because power LED, microcontroller etc. are on the same rail and the would not work with reversed supply voltage.
The board is pretty easy to fix if you have a way to desolder SMT parts. You likely blew the voltage regulator (unless one of the caps blew up). You can send the board back to me and I can fix it for you or you can buy LM1117-3.3 voltage regulator and replace it yourself. I use Texas Instruments but this part will work as well: AMS1117 3.3v Voltage Regulator IC SOT-223 - Pack of 10 D14-1.
If you haven't read this post: Connecting iGaging Scales to TouchDRO Controller , please do to make sure you connect the scales correctly.
Let me know if you need more info/help.
Regards
Yuriy